Piezoelectric microactuator for precise head positioning

ABSTRACT

A slider assembly for selectively altering a position of a transducing head with respect to a track of a rotatable disc having a plurality of concentric tracks includes a slider body having a main portion and a head portion separated by a gap. The head portion carries the transducing head. The slider body is arranged to be supported by a support structure over a surface of the rotatable disc. A pair of structural elements are disposed on opposite side surfaces of the slider body between the main portion and the head portion across the gap. At least one of the structural elements is a microactuator responsive to electrical control signals to selectively bend to alter the position of the head portion with respect to the main portion of the slider body. The structural elements may be complementary microactuators. The microactuators may be formed by a process involving forming the microactuators on a slider substrate or on a row of sliders, forming the microactuators on a slider stack, or separately forming the microactuators and attaching the microactuators to a slider stack.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority from Provisional Application No.60/055,874 filed Aug. 15, 1997 for “Piezoelectric Head MovingMicroactuator For Ultrahigh Track Density Magnetic Recording Drives” byV. Novotny.

BACKGROUND OF THE INVENTION

The present invention relates to a disc drive microactuator, and moreparticularly to a high resolution head positioning mechanism having oneor more piezoelectric elements attached to a slider as a bendablecantilever for selectively moving a head portion of the slider radiallywith respect to circumferential data tracks of a rotatable disc.

The track density, or radial spacing, between concentric data tracks onmagnetic discs continues to increase, requiring greater precision inhead positioning. Conventionally, head positioning is accomplished byoperating an actuator arm with a large-scale actuator motor, such as avoice coil motor, to position a head on a flexure at the end of theactuator arm. The large-scale motor lacks sufficient resolution andbandwidth to effectively accommodate high track-density discs. Thus, ahigh resolution head positioning mechanism is necessary to accommodatethe more densely spaced tracks.

One promising design for high resolution head positioning involvesemploying a high resolution microactuator in addition to theconventional low resolution actuator motor, thereby effecting headpositioning through dual-stage actuation. Various microactuator designshave been considered to accomplish high resolution head positioning,including piezoelectric, electromagnetic, electrostatic, capacitive,fluidic, and thermal actuators. Various locations for the microactuatorhave been suggested, including on the slider, on the gimbal, at theinterface between the gimbal and the slider, and on the actuator arm,for example. However, the previous designs all had shortcomings thatlimited the effectiveness of the microactuator, such as substantialperformance limitations or manufacturing complexities, which made themicroactuator designs impractical. An effective microactuator designmust provide high acceleration in positioning the head while alsogenerating sufficiently large and accurate displacements to preciselymove the head across several data tracks on the disc.

There is a need in the art for a microactuator design to provide highresolution head positioning with superior bandwidth performancecharacteristics that can be implemented by simple and readily availablemanufacturing processes.

BRIEF SUMMARY OF THE INVENTION

The present invention is a slider assembly for selectively altering aposition of a transducing head with respect to a track of a rotatabledisc having a plurality of concentric tracks. The slider assemblyincludes a slider body having a main portion and a head portionseparated by a gap. The head portion carries the transducing head. Theslider body is arranged to be supported by a support structure over asurface of the rotatable disc. A pair of structural elements aredisposed on opposite side surfaces of the slider body between the mainportion and the head portion across the gap. At least one of thestructural elements is a microactuator responsive to electrical controlsignals to selectively bend to alter the position of the head portionwith respect to the main portion of the slider body. The structuralelements are preferably complementary microactuators.

Another aspect of the present invention is a process of forming a pairof microactuators on each of a plurality of sliders. A slider substrateis formed comprising main portions of the sliders, and a sacrificiallayer is deposited on the slider substrate. Head portions each carryinga transducing head are then formed on the sacrificial layer. A row ofsliders is separated from the slider substrate, an air-bearing surfaceis formed on each of the sliders in the row, and notches are cut betweenindividual sliders in the row. Microactuators are formed between themain portions and the head portions of the sliders on side surfaces ofthe sliders in the notches. Alternatively, the microactuator processingmay be performed at the wafer level, prior to the steps of separatingthe slider substrate into rows and defining the air-bearing surfaces ofthe sliders in the rows. Individual sliders are separated from theslider row such that a pair of microactuators are on opposite sidesurfaces of each of the sliders. The sacrificial layer is removed toform a gap between the main portions and the head portions of thesliders.

A further aspect of the present invention is a process of forming amicroactuator on each of a plurality of sliders. A slider substrate isformed comprising main portions of the sliders, and a sacrificial layeris deposited on the slider substrate. Head portions each carrying atransducing head are then formed on the sacrificial layer. A row ofsliders is separated from the slider substrate, and an air-bearingsurface is shaped for each of the sliders in the row. Individual slidersare separated from the row of sliders, and a plurality of the individualsliders are glued together to form a slider stack. A plurality ofmicroactuators are formed on side surfaces of each of the sliders in theslider stack, and the sacrificial layer is etched away to form a gapbetween the main portions and head portions of each of the sliders. Thesliders are separated from each other by dissolving the glue.Alternatively, the plurality of microactuators may be separately formedand attached to the side surfaces of the sliders stack, and thenseparated into individual microactuators for each of the sliders in theslider stack.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a disc drive actuation system for positioning aslider over tracks of a disc.

FIG. 2 is a top view of a slider including piezoelectric microactuatorsfor high resolution head positioning according to the present invention.

FIG. 3 is a side view of the slider shown in FIG. 2.

FIG. 4 is an enlarged top view of a portion of the slider shown in FIG.2 illustrating the construction of the piezoelectric microactuatoraccording to a first embodiment of the present invention.

FIG. 5 is an enlarged top view of a portion of the slider shown in FIG.2 illustrating the construction of the piezoelectric microactuatoraccording to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a unimorph piezoelectric bending motorin its neutral position.

FIG. 7 is a diagram illustrating the unimorph piezoelectric bendingmotor of FIG. 6 in its actuated position.

FIG. 8 is a diagram illustrating a bimorph piezoelectric bending motorconfigured for parallel operation.

FIG. 9 is a diagram illustrating a bimorph piezoelectric bending motorconfigured for series operation.

FIG. 10 is a diagram of a typical slider substrate wafer.

FIG. 11 is a perspective view of a portion of the substrate wafer shownin FIG. 10 in enlarged detail, illustrating a process according to athird embodiment of the present invention.

FIG. 12 is a top view of a slider row processed according to a fourthembodiment of the present invention.

FIG. 13 is a side view of the slider row shown in FIG. 12, with aportion shown in enlarged detail to illustrate the microactuator.

FIG. 14 is a perspective view of a stack of sliders on which to formpiezoelectric microactuators according to a fifth embodiment of thepresent invention.

FIG. 15 is a perspective view of the stack of sliders shown in FIG. 10with piezoelectric microactuators formed thereon according to the fifthembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a top view of a disc drive actuation system 10 for positioningslider 24 over a track 34 of disc 30. Actuation system 10 includes voicecoil motor (VCM) 12 arranged to rotate actuator arm 16 around axis 14.Head suspension 18 is connected to actuator arm 16 at head mountingblock 20. Flexure 22 is connected to an end of head suspension 18, andcarries slider 24. Slider 24 carries a transducing head (not shown inFIG. 1) for reading and/or writing data on concentric tracks 34 of disc30. Disc 30 rotates around axis 32, so that windage is encountered byslider 24 to keep it aloft a small distance above the surface of disc30.

VCM 12 is selectively operated to move actuator arm 16 around axis 14,thereby moving slider 24 between tracks 34 of disc 30. However, for discdrive systems with high track density, VCM 12 lacks sufficientresolution and frequency response to position a transducing head onslider 24 over a selected track 34 of disc 30. Therefore, a higherresolution actuation device is necessary.

FIG. 2 is a top view and FIG. 3 is a side view of slider 24 includingpiezoelectric microactuator 42 a and structural element 42 b to enablehigh resolution positioning of head 41 according to the presentinvention. Slider 24 includes a head portion 40 carrying transducinghead 41 and also includes air gap or space 44 between head portion 40 ofslider 24 and the remaining portion of slider 24. Microactuator 42 a andstructural element 42 b are disposed on the side surfaces of slider 24near its distal end, connecting head portion 40 to the remainder ofslider 24. Microactuator 42 a is a structural element operable as abendable cantilever to alter the position of head portion 40 withrespect to main portion 38. Structural element 42 b is preferably amicroactuator similar and complementary to microactuator 42 a, but mayalternatively be a layer of structural material such as silicon nitride(Si₃N₄) or polysilicon, for example, to provide some flexibility whileprevent undesired vibrations that could affect the position oftransducing head 41. Transducing head 41 comprises an inductive writehead and/or a magnetoresistive read head, for example, as is well knownin the art. Transducing head 41 is desirably positioned directly over adata track on a rotating disc to read and/or write data from and/or tothe disc.

In operation, slider 24 is coarsely positioned adjacent a selected datatrack by activating VCM 12 to move actuator arm 16 (FIG. 1) carryingslider 24. To finely position transducing head 41 over the selectedtrack, control signals are applied to piezoelectric microactuator 42 ato cause bending of microactuator 42 a and consequent bending ofstructural element 42 b. When structural element 42 b is amicroactuator, control signals are also applied to microactuator 42 b tocause bending complementary to microactuator 42 a. Bending ofmicroactuators 42 a and 42 b is controlled to selectively alter theposition of transducing head 41 in the direction of arrows 46, therebyprecisely positioning transducing head 41 directly over the selectedtrack on the disc.

FIG. 4 is an enlarged top view of the distal portion of slider 24illustrating the construction of piezoelectric microactuator 42 aaccording to a first embodiment of the invention. Bottom electrode 50connects head portion 40 to the remainder of slider 24 across gap 44.Piezoelectric element 52 is formed on bottom electrode 50, and topelectrode 54 is formed on piezoelectric element 52. This configurationforms a cantilevered unimorph piezoelectric bending motor, the operationof which is described in detail below with respect to FIGS. 6 and 7.

FIG. 5 is an enlarged top view of the distal portion of slider 24illustrating the construction of piezoelectric microactuator 42 aaccording to a second embodiment of the invention. Structural layer 60connects head portion 40 to the remainder of slider 24 across gap 44.Buffer layer 62 is formed on structural layer 60, and adhesive layer 64is disposed on buffer layer 62. Bottom electrode 66 is formed onadhesive layer 64, and first piezoelectric element 68 is formed onbottom electrode 66. Shared electrode 70 is formed on piezoelectricelement 68. A second piezoelectric element 72 is formed on sharedelectrode 70, and top electrode 74 is formed on piezoelectric element72. An optional encapsulation layer 76 is formed over top electrode 74.This configuration of piezoelectric microactuator 42 a forms a bimorphpiezoelectric bending motor, the operation of which is discussed indetail later with respect to FIGS. 8 and 9.

In an exemplary embodiment, structural layer 60 is composed of siliconnitride (Si₃N₄) or polysilicon. Buffer layer 62 is preferably composedof silicon dioxide (SiO₂) or titanium dioxide (TiO₂). Adhesive layer 64is preferably composed of titanium (Ti) or tantalum (Ta). Bottomelectrode 66, shared electrode 70 and top electrode 74 are preferablyformed of platinum (Pt). Piezoelectric elements 68 and 72 may becomposed of zinc oxide (ZnO), lead zirconium titanate (PbZrTiO₃, knownas PZT), aluminum nitride (AlN) or polyvinylidene fluoride (PVDF). Thezinc oxide material requires no annealing or low temperature annealing,while the PZT material requires high temperature annealing.Piezoelectric elements 68 and 72 may be deposited by sputtering, sol geltechniques or laser deposition, as is known in the art.

FIG. 6 is a diagram of a cantilevered unimorph bending motor 80 in itsneutral position, and FIG. 7 is a diagram of cantilevered unimorphbending motor 80 in its actuated position. Unimorph bending motor 80 maybe implemented by piezoelectric microactuator 42 a described above withrespect to FIG. 4. Unimorph bending motor 80 includes bottom electrode82, piezoelectric element 84 and top electrode 86, and is restrained atone end by connection to a solid object such as slider 24. Terminal 88connects bottom electrode 82 to a first potential and terminal 90connects top electrode 86 to a second potential. Piezoelectric element84 is poled in the direction indicated by arrow 91.

In operation, when the potential difference between terminals 88 and 90(and consequently between bottom electrode 82 and top electrode 86) isapplied across piezoelectric element 84, the element contracts along itslength, forcing bending of piezoelectric element 84 and electrodes 82and 86 as indicated in FIG. 7. In this way, a deflection at the distaltip of bending motor 80 may be achieved. Conversely, application of anopposite potential difference between terminals 88 and 90 acrosspiezoelectric element 84 results in opposite bending and oppositedeflection at the distal tip of bending motor 80.

FIG. 8 is a diagram illustrating a cantilevered bimorph piezoelectricbending motor 100 configured for parallel operation. Bimorphpiezoelectric bending motor 100 may be implemented by piezoelectricmicroactuator 42 a described above with respect to FIG. 5. Bimorphpiezoelectric bending motor 100 is restrained at one end by connectionto a solid object such as slider 24. Bimorph piezoelectric bending motor100 includes bottom electrode 102, first piezoelectric element 104,shared electrode 106, second piezoelectric element 108, and topelectrode 110. In the “parallel” configuration depicted in FIG. 8,piezoelectric elements 104 and 108 are poled in the direction of arrows118 and 120. A first voltage is applied at terminal 112 to bottomelectrode 102, and at terminal 116 to top electrode 110. A secondvoltage is applied at terminal 114 to shared electrode 106. Thus, in the“parallel” configuration, piezoelectric element 108 will contract, andpiezoelectric element 104 will expand, in response to the first andsecond voltages applied at the terminals. The result is a bending motion(shown in dashed lines) of bimorph piezoelectric bending motor 100,since one end of the motor is restrained by connection to slider 24. Theamount of bending of the motor, and thus the amount of displacement oftransducing head 41 on head portion 40 (FIG. 2) is precisely controlledby the voltages applied to terminals 112, 114 and 116. Applying oppositevoltages to terminals 112, 114 and 116 causes similar bending in theopposite direction. Thus, bimorph piezoelectric bending motor 100 isable to provide high resolution positioning of head 41 over a selectedtrack of a disc.

FIG. 9 is a diagram illustrating a cantilevered bimorph piezoelectricbending motor 100 configured for series operation. Bimorph piezoelectricbending motor 100 may be implemented by piezoelectric microactuator 42 adescribed above with respect to FIG. 5. Just as in FIG. 8, bimorphpiezoelectric bending motor 100 includes bottom electrode 102, firstpiezoelectric element 104, shared electrode 106, second piezoelectricelement 108, and top electrode 110. Piezoelectric element 108 is poledin the direction of arrow 128 and piezoelectric element 104 is poled inthe opposite direction, shown by arrow 130. A first voltage is appliedat terminal 116 to piezoelectric element 108, and a second voltage isapplied at terminal 112 to piezoelectric element 104. As a result,bimorph piezoelectric bending motor 100 bends as indicated in dashedlines, since one end of the motor is restrained by the connection toslider 24. Applying opposite voltages to terminals 112 and 116 causessimilar bending in the opposite direction. The “series” configuration isthe simplest and most economical, since it requires only two connectionsto the outside surfaces of piezoelectric elements 104 and 108. However,the “series” configuration yields less deflection per volt of appliedpotential than the “parallel” configuration shown in FIG. 8. The“parallel” configuration is more complex, requiring three electricalconnections, the additional connection being made to shared electrode106. Either of the configurations shown in FIGS. 8 and 9 are acceptablefor effecting high resolution positioning of transducing head 41 (FIG.2) over a selected track of a disc.

FIG. 10 is a diagram of a typical slider substrate wafer 150. Substratewafer 150 is shown to comprise a plurality of portions 152 used to forma plurality of sliders 24, and has a thickness equal to a desired lengthof the sliders.

FIG. 11 is a perspective view of a portion 152 of substrate wafer 150.The portion 152 shows a 3×3 array of sliders 24. Transducing heads 41are formed on the top (trailing edge) surface of each slider 24 of wafer150, as is known in the art. The portion 152 further has layers formedthereon according to the present invention. In order to form sliders 24with a gap between main portions 38 and head portions 40, the substratewafer is used to define only main portions 38 of sliders 24. Sacrificiallayer 160 is deposited on the substrate wafer to define the region thatwill become the gap.

According to a third embodiment of the present invention, notches 172are cut between columns of sliders 24 before wafer 150 is cut (alongdotted lines 168) into slider rows. After notches 172 have been cut,multilayer piezoelectric microactuators are formed in notches 172. Thedetails of the process of forming the microactuators essentiallyidentical to the process discussed below with respect to FIG. 13, withlong strips of materials being formed for several sliders rather thanforming individual microactuators for each slider. Wafer 150 is thenready to be diced into slider rows along dotted lines 168, at whichpoint the air-bearing surfaces of sliders 24 are formed.

FIG. 12 is a top view, and FIG. 13 is a side view with a portion shownin enlarged detail, of a slider row 170 processed according to a fourthembodiment of the present invention, with structural elements 42 b beingimplemented as microactuators. Slider row 170 includes a plurality ofsliders 24 each having an air-bearing surface 171 and notches 172 cutbetween sliders 24. Notches 172 are shown as trapezoidal in shape, whichfacilitates sidewall deposition of microactuator layers between sliders;alternatively, notches 172 may be right-angle cuts if more sophisticatedsidewall deposition techniques are employed. Notches 172 are cut by adiamond saw, for example, and preferably do not extend through theentire height of sliders 24, so that sliders 24 remain attached to oneanother in slider row 170.

Microactuators 42 a and 42 b are formed in notches 172 on opposite sidesof sliders 24. Photolithography is performed to define the regions wherethe electrodes and piezoelectric materials of microactuators 42 a and 42b are to be deposited, with photoresist layers 177 being deposited toprotect transducing head 41. Bottom electrode 50 is then deposited innotch 172, also extending onto the top surface of sliders 24.Piezoelectric element 52 is deposited and annealed on bottom electrode50. If high annealing temperatures are required that are incompatiblewith the materials in transducing heads 41 of sliders 24, annealing maybe performed by a localized laser heating process, for example.Preferably, piezoelectric element 52 is composed of a material that doesnot require annealing temperatures that are incompatible with heads 41.Top electrode 54 is then deposited on piezoelectric element 52, andpoling of piezoelectric element 52 is performed at an elevatedtemperature. Bottom electrode 50 preferably extends on the top surfaceof sliders 24 beyond piezoelectric element 52 and top electrode 54 atregions 176, to provide easy access to bottom electrode 50 forelectrical connection thereto. After bottom electrode 50, piezoelectricelement 52 and top electrode 54 have been deposited, photoresist layers177 used in the photolithography process to define the microactuatorregions and protect transducing head 41 are removed and sliders 24 areseparated from slider row 170 by dicing at lines 174. Sacrificial layer160 between main portions 38 and head portions 40 of sliders 24 is alsoetched away to form the gap between those portions. Electricalconnections are made to the microactuator in a manner known in the art,such as through the flex circuit used to contact transducing head 41,and may be made on the top of the slider or on any other exposedsurfaces of bottom electrode 50 and top electrode 54. Althoughmicroactuators 42 a and 42 b are only shown in FIG. 13 with bottomelectrode 50, piezoelectric element 52 and top electrode 54 (asdescribed above with respect to FIG. 4), it should be understood thatmicroactuators 42 a and 42 b may be formed to include the layersdescribed above with respect to FIG. 5.

FIGS. 14 and 15 are perspective views of a stack of sliders 24,illustrating a process of forming microactuator 42 a and structuralelement 42 b on sliders 24 according to a fifth embodiment of thepresent invention. Sliders 24 are each formed as described above withrespect to FIGS. 11 and 12 by initially forming main portions 38 ofsliders 24, depositing sacrificial layer 160 on the distal surface ofmain portions 38, and forming head portions 40 on sacrificial layer 160,with head portions 40 carrying transducing heads 41. Sacrificial layer160 occupies the area that will become gap regions 44 between mainportions 38 of sliders 24 and head portions 40. Sliders 24 are dicedapart and then stacked and glued together lightly. Piezoelectricmicroactuator 42 a and structural element 42 b (which is preferablyanother microactuator) are either formed directly on slider rowassemblies, with the microactuator areas defined by photolithography,for example, on side surfaces of the slider stack, or are separatelyformed in strips or sheets and then attached to the side surfaces of theslider stack, yielding the structure shown in FIG. 15. Microactuator 42a may be formed on a structural layer (such as layer 60 in FIG. 5)deposited on the side surfaces of the slider stack, or may be formed orattached directly on the side surfaces of the stack. Structural element42 b may be a microactuator similar and complementary to microactuator42 a, or may be a structural layer composed of silicon nitride (S₃N₄) orpolysilicon, for example. Where the layers of microactuators 42 a and 42b are formed as sheets or strips along the side surfaces of the sliderstack, the material layers are cut at regions 180 so that microactuators42 a and 42 b do not extend all the way to the air-bearing surfaces ofsliders 24. In the case where microactuator 42 a and structural element42 b are formed on a separate substrate (which is subsequently removed)and attached to the slider stack, the multilayer sheets are ultimatelyseparated into individual microactuators on each of the sliders 24 by alaser, for example. This separate formation and transfer process avoidspotential temperature incompatibilities, since the potentially hightemperature annealing of the piezoelectric material is not performedproximate to transducing head 41. Sacrificial layer 160 is then etchedaway to form gaps 44 between the main portions of sliders 24 and headportions 40 of the sliders. The glue holding sliders 24 together is thendissolved, leaving each individual slider with piezoelectricmicroactuator 42 a and structural element 42 b on its side surfacesacross gap 44. Alternatively, the process described above could beperformed on each slider individually, thereby increasing the number ofsteps involved to attach the microactuators to the sliders buteliminating the steps of initially gluing the sliders together,separating the microactuators and ultimately dissolving the glue toseparate the sliders.

The present invention provides precise, high performance headpositioning, with high acceleration in moving the head and sufficientlylarge and accurate head displacement to cover several data tracks. Onlyhead portion 40 of slider 24 is moved by microactuator 42 a (andstructural element 42 b, when it is implemented as a microactuator),minimizing the total mass that is displaced and thereby enabling highacceleration of head 41. Additionally, moving only head portion 40 ofslider 24 allows the microactuator to cancel resonance effectsassociated with the actuator arm and flexure, eliminating any trackmisregistration effects due to vibrations or the like resulting fromthose resonances. The microactuators are also readily manufacturable bysimple existing fabrication techniques with only the addition of asacrificial layer on the slider, minimizing the incremental cost of themicroactuator-equipped disc drive.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A disc drive slider and transducing head assemblyfor selectively altering a position of the transducing head with respectto a track of a rotatable disc having a plurality of concentric tracks,comprising: a slider body having a discrete main portion and a discretehead portion separated by a gap, the head portion carrying thetransducing head, the slider body being arranged to be supported by asupport structure over a surface of the rotatable disc; and means forconnecting the head portion to the main portion of the slider body andfor selectively altering the position of the head portion with respectto the main portion of the slider body.
 2. A disc drive slider andtransducing head assembly for selectively altering a position of thetransducing head with respect to a track of a rotatable disc having aplurality of concentric tracks, comprising: a slider body having adiscrete main portion and a discrete head portion separated by a gap,the head portion carrying the transducing head, the slider body beingarranged to be supported by a support structure over a surface of therotatable disc; and a pair of structural elements on opposite sidesurfaces of the slider body between the main portion and the headportion across the gap, at least one of the structural elements being amicroactuator responsive to electrical control signals to selectivelybend to alter the position of the head portion with respect to the mainportion of the slider body.
 3. The slider assembly of claim 2, whereinthe microactuator comprises: a bottom electrode; a piezoelectric elementon the bottom electrode; and a top electrode on the piezoelectricelement.
 4. The slider assembly of claim 2, wherein the microactuatorcomprises: a bottom electrode; a first piezoelectric element on thebottom electrode; a shared electrode on the first piezoelectric element;a second piezoelectric element on the shared electrode; and a topelectrode on the second piezoelectric element.
 5. The slider assembly ofclaim 4, wherein the microactuator further comprises: a structural layeron one of the side surfaces of the slider body; and an adhesive layer onthe structural layer, the structural layer and the adhesive layersupporting the bottom electrode.
 6. The slider assembly of claim 5,wherein the microactuator further comprises: a buffer layer between thestructural layer and the adhesive layer.
 7. The slider assembly of claim4, wherein the microactuator further comprises: an encapsulation layerover the top electrode.
 8. The slider assembly of claim 2, wherein eachof the pair of structural elements is a microactuator responsive toelectrical control signals to selectively complementarily bend to alterthe position of the head portion with respect to the main portion of theslider body.
 9. The slider assembly of claim 8, wherein each of themicroactuators comprises: a bottom electrode; a piezoelectric element onthe bottom electrode; and a top electrode on the piezoelectric element.10. The slider assembly of claim 8, wherein each of the microactuatorscomprises: a bottom electrode; a first piezoelectric element on thebottom electrode; a shared electrode on the first piezoelectric element;a second piezoelectric element on the shared electrode; and a topelectrode on the second piezoelectric element.
 11. The slider assemblyof claim 10, wherein each of the microactuators further comprises: astructural layer on one of the side surfaces of the slider body; and anadhesive layer on the structural layer, the structural layer and theadhesive layer supporting the bottom electrode.
 12. The slider assemblyof claim 11, wherein each of the microactuators further comprises: abuffer layer between the structural layer and the adhesive layer. 13.The slider assembly of claim 10, wherein each of the microactuatorsfurther comprises: an encapsulation layer over the top electrode.